Telomerization is a chain reaction involving unsaturated compounds (monomers) and a substance that acts to propagate the reaction chain. More specifically, the term telomerization has been used to refer to a type of reaction in which one or more taxogens (i.e. one or more olefins such as ethylene, propylene, isobutylene, etc.) are reacted with one or more telogens to produce telomers according to the following schematic reaction:Q-H+nR0═R1→H—(R0—R1)n-Qwherein Q typically represents a monovalent organic moiety with a structure such that the single bond between the Q and H has a bond dissociation energy often in the range from 84 kcal/mol to 98 kcal/mole, and wherein each of R0 and R1 independently is an organic moiety, and R0 and R1 are linked by a double bond. R0═R1 schematically represents one or more unsaturated compounds comprising one or more carbon-carbon double bonds (e.g., ethylene, propylene, and other olefins in many instances); and —(R0—R1)— schematically represents a divalent alkylene moiety corresponding to R0═R1; and n is 1 or more. In some instances according to conventional practices, n is even 100 or more.
A telomerization reaction typically takes place in the presence of a free radical initiator. The compound Q-H is referred to as a telogen or chain transfer agent. Q-H represents a single telogen or a mixture of telogens if one more than one kind of telogen is used. The unsaturated R0═R1 is referred to as a taxogen. The product H—(R0—R1)n-Q is a telomer. The product is often a mixture of telomers of different chain lengths, e.g., telomers characterized by a variety of n values are produced. Telomerization is further described in U.S. Pat. Nos. 8,912,346; 8,779,164; 8,558,030; and 7,977,520. Bond dissociation energies of many hydrogen bonds is reported in Yu-Ran Lo, Handbook of Bond Dissociation Energies in Organic Compounds, CRC Press; 1 edition (Dec. 26, 2002).
It is very desirable to produce telomer products of limited weight, those with n<12 on a weight average basis, more preferably those in which a major portion (defined below) of the product is characterized by n<12. It also is desirable to produce a substantial amount of telomer products per gram of initiator used for the reaction. Unfortunately, achieving these goals individually as well as at the same time has been challenging. For example, U.S. Pat. No. 2,668,181 describes a telomerization process that requires excessive and uneconomical amounts of costly peroxide initiator (typically 0.1 to 0.3 moles per mole of product made) and typically produces less than 10 g of product per gram of initiator. The product mix also is undesirably diffuse and relatively high molecular weight. U.S. Pat. No. 4,156,101 also describes methods that give a low product yield per 1 gram of initiator and that result in a heavy complex non-selective product mixture.
Accordingly, there is a strong need for telomerization strategies that can produce telomer products that incorporate a limited number of added taxogen molecules, while at the same time also producing increased amounts of telomer products per gram of initiator.